Clamps



Jufiy i8, 196? L. J. CARVER 3,331,111

CLAMPS Filed May 6, 1966 United States Patent 3,331,111 (ILAMPS Leonard John Carver, Walsall, England, assignor to Carver & C0. (Engineers) Limited, Walsall, England, a British company Filed May 6, 1966, Ser. No. 548,260 2 Claims. (Cl. 24-263) ABSTRACT OF THE DISCLOSURE A C-clamp of the kind wherein coarse and fine adjusting means are provided for a movable jaw member slidably mounted on a frame yoke member carrying an opposed jaw, the coarse adjusting means comprising a series of teeth with which a fulcrum part of the movable jaw member is selectively engaged during the initial setting, and the fine adjusting means comprising a pressure member adapted to displace the movable jaw member angularly from said fulcrum part.

Heretofore, in most proposed C-clamps of the kind referred to, the frame yoke member has been in the form of a bar substantially of rectangular section carrying the teeth arranged in a single row along one face thereof. This arrangement, however, wherein the teeth extend across the full width of one face of the yoke bar, is ineflicient in that it tends to produce undesirable mechanical weaknesses, especially when it is desired to fabricate the clamps from lightweight alloys, and one object of the present invention is to provide an improved arrangement of ratchet teeth in such clamps.

According to the invention, in a C-clamp of the kind referred to, the teeth of the coarse adjusting means are disposed symmetrically about the median plane of the clamp in two parallel rows along the frame yoke member, the median planes of the teeth in said two rows mutually inclined and intersecting along a line in the median plane of the clamp and lying parallel to the longitudinal axis of the said frame yoke member; and the movable jaw member carries a fulcrum part of re-entrant V-shape which is adapted to be selectively engaged with pairs of said teeth lying opposite to each other in said two rows. With a frame yoke member in the form of a straight rectangularsectioned bar, the teeth are conveniently formed along each front corner edge of said bar so as to extend partly into the side faces and partly into the front face (that is, the face presented towards the jaws), of the bar.

FIGURE 1 of the accompanying drawings is a side elevation, partly in section, of a C-clamp in accordance with the present invention.

FIGURE 2 is a vertical section on line IIII, FIG- URE 1, showing the front edge of the frame bar in elevation.

FIGURE 3 is a horizontal section through the frame bar on line III-III FIGURE 1, showing the movable jaw in plan.

FIG. 4 is a horizontal section on line IV1V, FIG- URE 1.

FIGURE 5 is a horizontal section through the yoke bar on line V-V.

FIGURE 6 is a plan of the movable jaw member when removed from the bar.

FIGURE 7 is a fragmentary perspective view of the upper portion of the frame bar showing the arrangement of the teeth along the front corner edges of the bar.

Referring to the said drawings the C-clamp therein shown comprises a one piece J-shaped frame 1 cast in high-strength aluminium alloy, the straight upright limb of the frame being in the form of a susbtantially rectangular section bar 2 which is provided with ratchet teeth 3,331,1ll Patented July 18, 1967 as hereinafter described and which constitutes a yoke part, Whilst the offset lower part of the frame forms a fixed jaw arm 3.

This fixed jaw arm 3 terminates at its outer end in an integrally-formed lower clamping pad 4 which is adapted to co-operate with an opposed upper movable jaw pad 5 pivotally mounted on an arm 6 of a movable jaw member 7 which is slidably mounted upon the yoke part of the frame.

This movable jaw member 7 consists of a one-piece aluminium alloy casting and, in effect, forms a two-armed lever of which the one arm 6 carries the upper movable jaw pad 5, and the other arm is formed by a hollow boxlike body part having spaced-apart side walls 8 which are connected by upper and lower rear wall portions 9, 10 and which embrace the frame yoke bar 2 which is passed through the hollow interior of said body part. Integral with the lower rear wall portion 10 of the hollow body part is a rearwardly-projecting .boss 11 having a screwthreaded bore in which is fitted a screw 12 adapted to bear at its inner end on the rear face of the yoke bar 2 and thereby to provide for fine adjustment of the clamp, as later described. The head of this adjusting screw is conveniently fitted with a tommy bar 13 to facilitate manual operation.

The yoke bar 2 of the frame member is provided with a series of ratchet teeth 14 separated by notches 15 and which are arranged in two separate, spaced apart parallel rows along each of the two front corner edges of the yoke bar, the median planes A-A, AA, of the teeth in the two rows (see FIGURE 5) being mutually inclined so that the teeth are set obliquely and extend partly into the side faces and partly into the front face of the yoke bar. Moreover, the said teeth are symmetrically disposed with respect to the median plane BB (FIGURE 5) of the clamp which passes through the longitudinal axis of the yoke bar 2 and which also contains the line of intersection of the median planes A-A, A- of the two rows of ratchet teeth.

The hollow body part of the movable jaw member 7 is so formed as to fit over the yoke bar 2 of the frame with considerable clearance space, and on its interior face which forms the end of the arm 6 carrying the movable jaw pad 5 it has an integral projection 16, of re-entrant V-shape in plan, which forms a fulcrum part, the mutually-inclined side portions of said projection being adapted to be engaged with selected pairs of the ratchet teeth 14 lying opposite to each other in the two rows, in order to give a coarse setting adjustment of the movable clamp arm 6. The engagement of the fulcrum part 16 with the ratchet teeth in each setting is normally maintained by a blade spring 17 which is anchored at its lower end, at 18, to the lower rear wall portion 10 of the body part of the movable jaw member, the free upper end of this spring 17 being arranged to bear upon the rear face of the yoke bar 2 above the fulcrum part 16. Provided the fine adjustment screw 12 is first slackened off, however, the resistance of this blade spring can easily be overcome to enable the fulcrum part 16 to ride over, or be moved clear of, the ratchet teeth 14 so that a quick adjustment of the coarse setting can rapidly be obtained by sliding the movable jaw member 7 along the yoke bar to a new position.

In each coarse setting, a fine adjustment of the clamp is achieved by screwing the fine adjustment screw 12 inwards against the rear face of the yoke bar 2 so that the arm 6 of the movable jaw member is caused to turn angularly about the said fulcrum part 16.

With the arrangement of the ratchet teeth as described, the stress resistance and strength of a given yoke bar can be made considerably higher than with the alternative arrangement of a single row of ratchet teeth which extend across the width of the front face of the bar, and this improvement in equivalent strength is especially advantageous when it is desired to fabricate the parts from lightweight alloy. Also, the re-entrant V-shaped form 01' configuration of the fulcrum part 16 tends to produce a strong centralising action when engaged under pressure with the ratchet teeth which assists in aligning the clamping pad 5 of the movable jaw arm with the fixed clamping pad 4 of the frame member.

I claim:

1. A C-clamp comprising a frame yoke member carrying a fixed jaw; a movable jaw member slidably mounted on said frame yoke member; two parallel rows of rack teeth on said yoke member, the same being disposed symmetrically about the median plane of the yoke member with the median planes of the teeth in the two rows mutually inclined and intersecting along a line in the median plane of the clamp; a fulcrum part on the movable jaw member of re-entrant V-shape in plane for selective engagement with opposite teeth in the two rows to give a coarse adjustment of the movable jaw member; and a pressure member adapted to displace the said movable jaw member angularly about the said fulcrum part to provide a fine adjustment.

2. A C-clamp according to claim 1, wherein the frame yoke member consists of a straight bar of substantially rectangular section having the teeth formed along each front corner edge of said bar so as to extend partly into the side faces and partly into the front face of the bar.

References Cited UNITED STATES PATENTS 153,133 7/1874 Wagoner 269-l71 248,949 11/1881 Pope 269285 957,520 5/1910 Stearns 269-285 FOREIGN PATENTS 863,441 3/1961 Great Britain.

WILLIAM FELDMAN, Primary Examiner.

DONALD A. GRIFFIN, Examiner. 

1. A C-CLAMP COMPRISING A FRAME YOKE MEMBER CARRYING A FIXED JAW; A MOVABLE JAW MEMBER SLIDABLY MOUNTED ON SAID FRAME YOKE MEMBER; TWO PARALLEL ROWS OF RACK TEETH ON SAID YOKE MEMBER, THE SAME BEING DISPOSED SYMMETRICALLY ABOUT THE MEDIAN PLANE OF THE YOKE MEMBER WITH THE MEDIAN PLANES OF THE TEETH IN THE TWO ROWS MUTUALLY INCLINED AND INTERSECTING ALONG A LINE IN THE MEDIAN PLANE OF THE CLAMP; A FULCRUM PART ON THE MOVABLE JAW MEMBER OF RE-ENTRANT V-SHAPE IN PLANE FOR SELECTIVE ENGAGEMENT WITH OPPOSITE TEETH IN THE TWO ROWS TO GIVE A COARSE ADJUSTMENT OF THE MOVABLE JAW MEMBER; AND A PRESSURE MEMBER ADAPTED TO DISPLACE THE SAID MOVABLE JAW MEMBER ANGULARLY ABOUT THE SAID FULCRUM PART TO PROVIDE A FINE ADJUSTMENT. 